Please show full solutions

Part 1

solve each of the identities below

1. sin 3a cos a - cos 3a sin a = 2 sin a cos a

2. sec x cot x = csc x

3. 2tan x (1 - sin^2 x) = sin2x

4. cos x tan^3 x = sin x tan^2 x

Part 2

Determine exact value for both

1.1+tan37tan35tan37tan35

2.cos125cos4+sin125sin4

Part 3

for the equation 2secx + 8 = 4

solve for x, where0x2